The present invention relates to a valve lapping tool of the type which is used to help seat the valve of an internal combustion engine.
When replacing and/or repairing the valves of an internal combustion automobile engine, typically, each seat of the engine block, upon which the head of a valve will be seated, must be ground in a precision manner so that the underside of the valve head will properly engage the valve seat. That is, a typical internal combustion engine valve includes a head with an axially projecting stem. The head may have a flat or shaped top surface and an outer edge which is ground or shaped to fit tightly against a seat honed in the valve passage or chamber of an engine block. Machine honing of the mating valve head and engine block seating surfaces does not necessarily provide a totally congruent fit of the valve head against the engine block valve seat. Consequently, the practice has been to insert a lapping compound on the engine block valve seat and to subsequently rotate the head of the valve against the valve seat to thereby shape the opposed parts in a manner which will provide an extremely tight seal when the valve is closed on the engine block valve seat.
Tools utilized to effect the movement of the valve against the valve seat include valve lapper tools. FIGS. 1 and 2 of the application depict versions of valve lapper tools. Typically, as shown in FIG. 1, the tool includes a handle with rubber suction cups at the opposite ends of the handle. The handle is made from wood turned on a lathe to an appropriate shape. Alternatively, as depicted in FIG. 2, the handle may be made from extruded plastic material and will have a uniform cross-section along its entire length with rubber suction cups affixed to each end of the extruded handle.
In practice, the lapper tool is positioned so that a suction cup will fit over and adhere to the top surface of a valve. The tool handle is then rotated between the hands of the mechanic to thereby rotate the valve about the axis of the valve stem causing the underside of the valve to lap against the valve seat and thereby provide a seal of extremely high quality.
The particular tools described are quite useful. However, wooden handled tools often lack necessary durability. Moreover, the wood turning operation to form the handle may, if not properly performed, cause the development of splinters or fissures in the wood. Finally, a wooden handle is susceptible to damage from certain fluids and moisture.
The extruded plastic handle has the disadvantage a very uncomfortable shape for a manual operation. Because it does not have a variable cross-section along its length, it is not as easily controlled or manipulated as a valve lapping tool using a handle made by a wood turning operation. Thus, there has developed the need for an improved valve lapping tool or valve lapper of the type generally described, but one which provides enhanced durability and utility.